The embodiments described herein relate generally to wind turbines, and more particularly, to systems and methods for lubricating gears in a wind turbine, especially components of pitch and yaw assemblies.
At least some known wind turbines include a bearing coupled between a blade and a hub, and a pitch assembly for use in positioning the blade attached to the bearing. The pitch assembly is operated to adjust the pitch of the blade. Over time, the pitch bearing teeth of the bearing may become worn. As the pitch bearing teeth become worn, the pitch assembly becomes less effective in operating to adjust the pitch of the blades. In some cases, the pitch bearing teeth can fail resulting in the inability of the pitch drive system to rotate the blade. In at least some known wind turbines, the entire hub must be removed from the wind turbine, prior to removing each blade and adjusting the pitch bearing to engage new pitch bearing teeth. In some wind turbines, the blades are between 60 and 100 meters in length, and as such, replacing worn pitch bearing teeth can be costly and time-consuming.
During operation worn pitch bearing teeth may enable a blade to undesirably move from a desired pitch setting. In some cases, the blades of the wind turbine asymmetrically load the hub and rotor shaft, and may cause the rotor to become imbalanced. Depending on the extent of the rotor imbalances, increased loads may be induced to the rotor and other drive train components. Moreover, the rotor's position with respect to the wind may induce increased loads on the rotor and other drive train components.